Whitelist your production domain for browser API keys and client IDs in
the Google Developer Console.

Whitelist your production domain in the Auth tab of the
Firebase console panel.

Know your plan limits

All The Realtime Database, Storage, and Hosting features have
hard usage caps on the Spark and Flame plans. Hitting these limits may mean
that your app stops working as you intend. Consider upgrading to the Blaze
plan to remove these limits. See the pricing page for more details.